Divergent Synthesis of Six Recent Berkeleylactones.

The six recently isolated berkeleylactones E, J, K, M, N, and O were synthesized for the first time by a divergent strategy starting from a common intermediate in our synthesis of berkeleylactone A. Key features were the stereoselective formation of the γ,δ-dihydroxy-α,β-unsaturated ester moiety and the development of a general protection group strategy. Along the way we also established a short high-yielding formal synthesis of the often-synthesized antibiotic A26771B.